How do I disassemble this builders level transit?

November 14, 2018 4:30 PM

I have an old David White level transit labeled as a Meridian LT6-900 (although the manual that comes with it says it is a Meridian 8830, which is what the level looks like). The focus knob suddenly will not turn.

The focus knob turns an internal gear which has seized up. The internal gear mechanism has to be removed out of one end or the other of the telescope tube. The manual only shows external parts, and I can't find anything on line with internal parts descriptions or disassembly instructions. I've tentatively removed some brass fittings and two small lenses through the eyepiece end, but I'm not sure of the exact orientation to replace them, or how to proceed further to get the gearing out. I've also not been able to find a discussion group or other forum on line where I might get help. I'm handy, but I'd feel better with some good advice. And, yeah, I borrowed the level from a friend.

posted by Jackson to Technology (2 answers total)

There are plenty of places that do this service. I use some precise measuring instruments in my hobby, when I have problems with them, I send them off to a pro. It usually doesn't cost much. Google "transit repair".
If you are already lost, "not sure of the exact orientation to replace them", maybe it's time for a pro.
posted by rudd135 at 5:14 PM on November 14, 2018

I have an old dumpy level and I’m not going to take it apart until I have to. My suspicion is that the focusing mechanism is the same across many similar items. I take it you’ve already tried compressed air and a tiny amount of oil? What about cooling it in a freezer (a semi-drastic measure but since its open and borked already you don’t have a lot to lose).

In case it helps: here is a general schematic I found. Another thing that might help is knowing that “builder’s level” and “dumpy level” are basically synonyms. While “transit” is often used for these, in the narrow sense it should be reserved for a device that can turn up and down as well (though they probably use similar focal mechanisms)

General advice: take lots of photos and make your own diagrams before proceeding further. We’ve all made the mistake you have made with disassembly and we all swear it will be the last time but... yeah I sympathize.

Also, if you don’t get enough help here, consider posting on telescope fora: it’s basically a small telescope with a nice swivel and a spirit level, so their expertise may well be relevant enough to help.

Finally, the lenses are certainly racially symmetric, right? They may also have no front or back. I don’t think mine do, but of course some lenses do, my apologies if this is visually obvious in your case; but again the telescope enthusiasts may help, if you can provide them with plenty of photos and diagrams.
posted by SaltySalticid at 5:16 PM on November 14, 2018